This invention relates in general to the detection of leaks through a structure surface and, more specifically to a leak detection method using a releasable film over the surface of a pressurized structure which detects leaks by the formation of bubbles in the film at leak locations.
Several different methods are in use for detecting leaks in pressure vessels, fuel tanks, and other vessels containing fluids. Most commonly, a gas filled pressurized vessel is checked for leaks by coating the surface with a soap solution that bubbles wherever the gas is leaking. While effective in many cases, this method has several disadvantages. Forming a uniform coating, with no dry spots, is often difficult. Very small, slow leaks often cannot be detected because of the length of time required for formation of a visible bubble and drying of the solution over that period. Soap solutions may contaminate or otherwise damage the surface being tested. Excellent operator skill, vision and patience are required for effective leak detection with soap solutions.
More recently, other leak detection systems have been developed, such as helium mass spectrometers, gas sniffers and ultrasonic detectors. While effective in most cases, these systems do not have the sensitivity to find very small leaks and are expensive and require considerable training and skill to use.
The prior methods require that the surface of the structure be marked at the leak locations for later repair. The marks may damage the surface, may be inadvertently wiped away prior to repair and large leaks may mask nearby smaller leaks.
Thus, there is a continuing need for improved leak detection methods that can find very small leaks, reliably and accurately, and permits easy and convenient retesting after initial repairs.